Lighting power density compares connected lighting load with the assessed area.
Lighting power density is connected lighting load divided by area, usually expressed in W/m2. It describes load intensity, not visual performance.
Technical meaning
Lighting power density compares input watts for a lighting group with the area served by that group.
It is normally written as watts per square metre and should be read beside the area boundary and operating schedule.
Lighting power density boundaryLighting power density is a load-per-area record for one boundary before hours, controls or energy are added.
Calculation use
W/m2 equals connected lighting watts divided by the assessed square metres.
Energy estimates still need operating hours and tariff, while lighting quality still needs illuminance, uniformity, glare and task notes.
Not the same as
Lighting power density is not brightness. A low W/m2 result can still under-light a task plane.
Lighting power density is not annual energy by itself because operating hours and controls can change kWh.
Australian context
Australian energy and room notes should keep W/m2, annual kWh and lighting quality notes distinct so load efficiency is not confused with visual suitability.
Examples
Example
Value
Planning note
48 W over 12 m2
4.0 W/m2
Load density only; check lux and glare separately.
216 W over 40 m2
5.4 W/m2
Useful for comparing zones with similar tasks.
Accent group
separate W/m2
Directional loads should not be hidden inside broad ambient figures.
Lighting power density is formula arithmetic. Any regulated energy or project benchmark should be checked through the appropriate Australian documents.